| Malhavin Property Developments Limited | Construction | 2017 |
| Malinga Care Ltd | Health & social care | 2023 |
| Mallard Close Management Company Limited | Real estate | 2004 |
| Mallard FS Ltd | Financial services | 2021 |
| Mallei Limited | Real estate | 2019 |
| Mallins Associates Ltd | Professional & scientific | 2021 |
| Malmesbury Animal Sanctuary CIC | Agriculture & fishing | 2022 |
| Malmesbury Properties Limited | Real estate | 2020 |
| Malmo Consultancy Ltd | Information & communication | 2023 |
| Malmo Properties Ltd | Real estate | 2024 |
| Malthouse Creations Limited | Information & communication | 2016 |
| Malthouse Nursery Limited | Health & social care | 2020 |
| Maltnoz Limited | Health & social care | 2011 |
| Malwal Ltd | Construction | 2018 |
| MAM Services Ltd | Health & social care | 2020 |
| Mambeva Trading Ltd | Professional & scientific | 2019 |
| Mamre Oaks Limited | Real estate | 2020 |
| MAN Financial Services UK Limited | Financial services | 2023 |
| MAN Truck and BUS UK Limited | Wholesale & retail | 1992 |
| Mana's IPL Limited | Other services | 2019 |
| Mana's Property Consultancy Limited | Real estate | 2014 |
| MANAGEMENT28 Ltd | Information & communication | 2004 |
| Manchester Airport Business Park Management Limited | Real estate | 2001 |
| Manchester Road Kebab Ltd | Hospitality | 2019 |
| Manchido Collective Ltd | Real estate | 2025 |
| Manchip Consultancy Limited | Health & social care | 2020 |
| Mandarin Asset Management Limited | Professional & scientific | 2011 |
| Mandarin Components Limited | Wholesale & retail | 2012 |
| Mandarin Europe Limited | Construction | 2007 |
| Mandora Services Ltd | Administrative & support | 2024 |
| Manesty Developments Limited | Wholesale & retail | 1987 |
| Maniana-Mns Ltd | Transport & logistics | 2019 |
| Manmik Investments Ltd | Real estate | 2025 |
| Manmik Ltd | Construction | 2018 |
| Manna Care Services Ltd | Health & social care | 2023 |
| Manners Property Management Limited | Real estate | 2023 |
| Mannington Health & Safety Ltd | Health & social care | 2026 |
| Mannington House Residents Limited | Households | 1974 |
| Mannington Supplies (Weston-Super-Mare) Ltd | | 2007 |
| Mannington Supplies Limited | Wholesale & retail | 2003 |
| Mannpower and Light Limited | Energy | 2014 |
| Manodum Smart Solution Ltd | Transport & logistics | 2019 |
| Manodum Transport Ltd | Transport & logistics | 2013 |
| Manoftom Ltd | Health & social care | 2017 |
| Manondo Ltd | Health & social care | 2016 |
| Manor Court (Fairford) Management Company Limited | Households | 1987 |
| Manor Farm Property Management Company Limited | Extraterritorial | 2005 |
| Manor Farm Winterbourne Bassett Limited | Households | 1997 |
| Manor Garage Swindon Ltd | Wholesale & retail | 2017 |
| Manor House Residents Limited | Professional & scientific | 2008 |
| Manor Motor Hub Ltd | Wholesale & retail | 2025 |
| Manor Property Services (Swindon) Limited | Real estate | 2020 |
| Manorwood Leisure Developments Ltd | Hospitality | 2025 |
| Mansfield Associates (Wiltshire) Limited | Education | 2016 |
| Mantonfest | Arts & recreation | 2016 |
| Many Ltd | Transport & logistics | 2023 |
| Maple (147) Limited | Professional & scientific | 2000 |
| Maple (235) Limited | Households | 2004 |
| Maple Sugar Music Ltd | Arts & recreation | 2025 |
| Maples Property Co Ltd | Professional & scientific | 2011 |
| Mapufien Ltd | Real estate | 2026 |
| Maranatha Consultants Ltd | Information & communication | 2017 |
| Maranatha Properties Ltd | Real estate | 2022 |
| Maranatha Ventures Limited | Transport & logistics | 2011 |
| March-Ts Limited | Professional & scientific | 2024 |
| Marcin K Logistics Ltd | Transport & logistics | 2019 |
| Marco 31 Ltd | Health & social care | 2023 |
| Marco GRI Ltd | Transport & logistics | 2023 |
| Mardegan Maid 4 YOU Ltd | Administrative & support | 2022 |
| Mare Ventus Ltd | Administrative & support | 2009 |
| Mareksprops Ltd | Real estate | 2024 |
| Marelle Services Ltd | Professional & scientific | 2019 |
| Marfleet Lane Store PVT Ltd | Wholesale & retail | 2025 |
| Margaret Flood Limited | Professional & scientific | 2019 |
| Margaret’S Prep Kitchen Ltd | Hospitality | 2025 |
| Margum Tyres Ltd | Wholesale & retail | 2019 |
| Maria Fish Bar Ltd | Hospitality | 2019 |
| Marian KC Limited | Transport & logistics | 2020 |
| Marina Software Limited | Information & communication | 2022 |
| Marine Drive Ltd | Construction | 2019 |
| Mario Dumitru Limited | Health & social care | 2021 |
| Marios Pizza Basset Ltd | Hospitality | 2026 |
| Marius JR Transport Ltd | Transport & logistics | 2019 |
| Marius Wash Center Ltd | Administrative & support | 2025 |
| Mariusz Trans Ltd | Transport & logistics | 2023 |
| Mark Allsop Thatching Limited | Agriculture & fishing | 2014 |
| Mark Bidgood Plumbing and Heating Ltd | Manufacturing | 2011 |
| Mark Cooper Consultancy Ltd | Professional & scientific | 2026 |
| Mark Cooper Engineering Ltd | Professional & scientific | 2018 |
| Mark Fletcher Productions Limited | Agriculture & fishing | 1993 |
| Mark Rogers Consultancy Ltd | Professional & scientific | 2017 |
| Mark Simon Joseph Lane Limited | Financial services | 2025 |
| Mark Speed Trans Ltd | Transport & logistics | 2015 |
| Mark Todd Eventing Limited | Arts & recreation | 2011 |
| Mark Underwood Consulting Limited | Professional & scientific | 2025 |
| Mark's One Ltd | Administrative & support | 2015 |
| Market Lavington Management Company Limited | Households | 1989 |
| Market Right Ltd | Real estate | 2007 |
| Marketing Helpdesk Ltd | Administrative & support | 2023 |
| Marketing Managed Ltd | Information & communication | 2014 |